From 9560a48ecc0c20d87bc458a6db77fba651605819 Mon Sep 17 00:00:00 2001 From: Jiahui Cen Date: Wed, 23 Oct 2019 11:47:37 +0800 Subject: [PATCH] migration/multifd: fix destroyed mutex access in terminating multifd threads One multifd will lock all the other multifds' IOChannel mutex to inform them to quit by setting p->quit or shutting down p->c. In this senario, if some multifds had already been terminated and multifd_load_cleanup/multifd_save_cleanup had destroyed their mutex, it could cause destroyed mutex access when trying lock their mutex. Here is the coredump stack: #0 0x00007f81a2794437 in raise () from /usr/lib64/libc.so.6 #1 0x00007f81a2795b28 in abort () from /usr/lib64/libc.so.6 #2 0x00007f81a278d1b6 in __assert_fail_base () from /usr/lib64/libc.so.6 #3 0x00007f81a278d262 in __assert_fail () from /usr/lib64/libc.so.6 #4 0x000055eb1bfadbd3 in qemu_mutex_lock_impl (mutex=0x55eb1e2d1988, file=, line=) at util/qemu-thread-posix.c:64 #5 0x000055eb1bb4564a in multifd_send_terminate_threads (err=) at migration/ram.c:1015 #6 0x000055eb1bb4bb7f in multifd_send_thread (opaque=0x55eb1e2d19f8) at migration/ram.c:1171 #7 0x000055eb1bfad628 in qemu_thread_start (args=0x55eb1e170450) at util/qemu-thread-posix.c:502 #8 0x00007f81a2b36df5 in start_thread () from /usr/lib64/libpthread.so.0 #9 0x00007f81a286048d in clone () from /usr/lib64/libc.so.6 To fix it up, let's destroy the mutex after all the other multifd threads had been terminated. Signed-off-by: Jiahui Cen Signed-off-by: Ying Fang Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/ram.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/migration/ram.c b/migration/ram.c index 278b2ff87a..7221f54139 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1053,6 +1053,10 @@ void multifd_save_cleanup(void) if (p->running) { qemu_thread_join(&p->thread); } + } + for (i = 0; i < migrate_multifd_channels(); i++) { + MultiFDSendParams *p = &multifd_send_state->params[i]; + socket_send_channel_destroy(p->c); p->c = NULL; qemu_mutex_destroy(&p->mutex); @@ -1336,6 +1340,10 @@ int multifd_load_cleanup(Error **errp) qemu_sem_post(&p->sem_sync); qemu_thread_join(&p->thread); } + } + for (i = 0; i < migrate_multifd_channels(); i++) { + MultiFDRecvParams *p = &multifd_recv_state->params[i]; + object_unref(OBJECT(p->c)); p->c = NULL; qemu_mutex_destroy(&p->mutex); -- 2.11.4.GIT